Messages in this thread Patch in this message |  | | Date | Wed, 5 Oct 2016 18:44:32 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH V2 2/2] fs/super.c: don't fool lockdep in freeze_super() and thaw_super() paths |
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On 10/05, Dave Chinner wrote: > > On Tue, Oct 04, 2016 at 01:43:43PM +0200, Oleg Nesterov wrote: > > > plus the following warnings: > > > > [ 1894.500040] run fstests generic/070 at 2016-10-04 05:03:39 > > [ 1895.076655] ================================= > > [ 1895.077136] [ INFO: inconsistent lock state ] > > [ 1895.077574] 4.8.0 #1 Not tainted > > [ 1895.077900] --------------------------------- > > [ 1895.078330] inconsistent {IN-RECLAIM_FS-W} -> {RECLAIM_FS-ON-W} usage. > > [ 1895.078993] fsstress/18239 [HC0[0]:SC0[0]:HE1:SE1] takes: > > [ 1895.079522] (&xfs_nondir_ilock_class){++++?-}, at: [<ffffffffc049ad45>] xfs_ilock+0x165/0x210 [xfs] > > [ 1895.080529] {IN-RECLAIM_FS-W} state was registered at: > > And that is a bug in the lockdep annotations for memory allocation because it > fails to take into account the current task flags that are set via > memalloc_noio_save() to prevent vmalloc from doing GFP_KERNEL allocations. i.e. > in _xfs_buf_map_pages():
OK, I see...
I'll re-test with the following change:
--- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -2867,7 +2867,7 @@ static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags) return; /* We're only interested __GFP_FS allocations for now */ - if (!(gfp_mask & __GFP_FS)) + if ((curr->flags & PF_MEMALLOC_NOIO) || !(gfp_mask & __GFP_FS)) return;
Hmm. This is off-topic and most probably I missed something... but at first glance we can simplify/improve the reclaim-fs lockdep annotations:
1. add the global "struct lockdep_map reclaim_fs_map"
2. change __lockdep_trace_alloc
- mark_held_locks(curr, RECLAIM_FS); + lock_map_acquire(&reclaim_fs_map); + lock_map_release(&reclaim_fs_map);
3. turn lockdep_set/clear_current_reclaim_state() into
void lockdep_set_current_reclaim_state(gfp_t gfp_mask) { if (gfp_mask & __GFP_FS) lock_map_acquire(&reclaim_fs_map); } void lockdep_clear_current_reclaim_state(gfp_t gfp_mask) { if (gfp_mask & __GFP_FS) lock_map_release(&reclaim_fs_map); } and now we can remove task_struct->lockdep_reclaim_gfp and all other RECLAIM_FS hacks in lockdep.c. Plus we can easily extend this logic to check more GFP_ flags.
No?
Oleg.
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